A number of U.S. patents relate to the production of benzene/toluene/xylene (BTX) mixtures from various feeds, and the disproportionation of toluene or xylene to benzene and other aromatics.
U.S. Pat. No. 3,716,596, Bowes, Feb. 13, 1973, discloses alkylaromatic dealkylation using ZSM-4.
U.S. Pat. No. RE 29,857 of U.S. Pat. No. 3,790,471, Argauer, Feb. 5, 1974, discloses toluene disproportionation using ZSM-5.
U.S. Pat. No. 3,945,913, Brennan, Mar. 23, 1976, discloses the preparation of BTX from alkylaromatics having nine or more carbon atoms using ZSM-5.
U.S. Pat. No. 4,066,531, Owen, Jan. 3, 1978, discloses using ZSM-5 to process a heavy reformate feedstock (C.sub.8.sup.+ alkylaromatics) from which benzene has been removed to produce BTX.
The preceding patents relate to disproportionation reactions. The well-known dealkylation reactions of the art, typically operate at very severe conditions. The usual feed, toluene, is typically heated to 590.degree. C. to 650.degree. C. at pressures of from 25-40 bar for both thermal and catalytic processes; thermal dealkylation is performed at temperatures up to 760.degree. C.